LAUSR

OBJECTIVE To explore the effect of miR-543-3p on the recovery of locomotor function after spinal cord injury (SCI) by regulating tumor necrosis factor superfamily member 15 (TNFSF15) mediated inflammation and apoptosis. MATERIALS AND METHODS Macrophages were isolated from the abdominal cavity of 2-3 months old Sprague-Dawley (SD) rats and cultured. The levels of miR-543-3p, tumor necrosis factor superfamily member 15 (TNFSF15), TNF-like molecule 1A (TL1A) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) after transfection of miR-92b-5p into activated macrophages were detected by quantitative Real-time polymerase chain reaction (qRT-PCR). Moreover, the mRNA expressions of miR-543-3p, TNFSF15, TL1A and NF-κB after SCI in rats were detected by qRT-PCR. Meanwhile, the protein expressions of tumor necrosis factor (TNF-α), interleukin-1 β (IL-1β) and Caspase8 were detected by Western blot. After intrathecal injection of miR-543-3p mimics, the mRNA expressions of miR-543-3p, TNFSF15, TL1A and NF-κB and the protein expressions of TNF-α, IL-1β and Caspase8 in spinal cord injured area of mice were measured by qRT-PCR and Western blot, respectively. Basso Beattie Bresnahan (BBB) locomotor rating scale was used to determine the recovery of locomotor function after spinal cord injury and injection of miR-543-3p mimics. RESULTS Compared with inactivated cells, the expression of miR-543-3p in activated macrophages was significantly declined. However, the levels of TNFSF15, TL1A and NF-κB were significantly elevated. The expressions of TNFSF15, TL1A and NF-κB were remarkably downregulated after transfection of miR-543-3p. In addition, the level of miR-543-3p was significantly downregulated, accompanied by an increase in TNFSF15, TL1A and NF-κB in SCI rats. Accordingly, the protein levels of TNF-α and IL-1β and Caspase8 were also significantly increased. However, the expressions of TNFSF15, TL1A and NF-κB were significantly down-regulated in rats injected with miR-543-3p mimics, whereas the protein levels of TNF-α and IL-1β and Caspase8 were significantly suppressed. Finally, compared with SCI group, the recovery of locomotor function in miR-543-3p mimics administration group was significantly improved. CONCLUSIONS After SCI, miR-543-3p can inhibit the activity of NF-κB by suppressing the inflammatory aggravation of TNFSF15 and decreasing its product TL1A. MiR-543-3p leads to the improvement of neuron protection and locomotor function via attenuating inflammatory reaction and cell apoptosis.